What is GIS?

Nov. 30, 2014
written by George Williams, MBA, PMP, GISP of Applied GeoData LLC
edited by K-Y Su of NowAmFound GeoGraphics

Last week (Nov. 17th) was Geography Awareness Week.  During that week, Nov. 19th was GIS Awareness Day.  I thought I would take this opportunity to start a blog about GIS and the importance of Geographic Data for all human endeavors – business (operations, economics, and marketing), natural resources management, engineering, and government.    

I often hear the question from people, and most surprisingly from information technology (IT) and business intelligence (BI) professionals, asking me “What is GIS?”.  So let’s start there.

GIS stands for Geographic Information Systems.  A Geographic Information System is a computing technology that evolved from Computer Aided Design (CAD) software in the 1970s, as CAD was initially used to draw maps. However, GIS evolved away from simply drawn visualization of static maps with the addition of database technology.

Figures 1a and 1b show how GIS integrates computing hardware (PCs, Workstations, Servers of various types, Storage Area Networks, Large Print and Plotting devices, etc.), GIS software, and data stored in a spatially-enabled (Enterprise or Desktop) databases.  GIS is a very powerful tool for visualizing geographic data, planning, managing geographically dispersed resources, and to measure and analyze geographic features and especially how they interrelate with each other. 

                                                                                FIGURE 1a

                                               

Figure 1b

A typical ESRI ArcGIS configuration for Client – Server distributed GIS

People often confuse GIS with GPS (Global Positioning System).  GPS is related to GIS, and is important for locating features on the earth accurately.  But, GPS is not the same as GIS.

Figure 2
Global Positioning System – Satellite system used to locate earth features.

Figure 2 displays the basis of a GPS which is a system of satellites in synchronous earth orbit that communicate with devices on the earth’s surface to provide precise locations.  There are several GPS systems available that relay GPS location information and geo-locate positions on a map (many smart phones have apps for this).  But GIS is more of a tool for spatial data analysis, than simple map visualization.  GIS consumes GPS data in order to increase location data accuracy – thereby increasing accuracy of measurements, routing algorithms, and areal calculations for example.

There are several software vendors that produce and sell GIS software.  Some of these firms are:

·      ESRI (Environmental Science & Research Institute – providing the ArcGIS suite of products

·      Pitney Bowes providing the MapInfo GIS product

·      Bentley GIS  provides Mapping Software (Desktop, Enterprise, and Industry specific)

·      Intergraph provides GeoMedia GIS software, and

·      Open Source GIS provides (QGIS, GRASS, and several others)

To date Esri (based in Redlands, CA) is the market leader of the GIS software vendors with significant inroads into global government agencies.  However new commercial and Open source vendors are cutting into that lead.

Personally, what first impressed me about GIS was its ability to perform Thematic Mapping.  Thematic Mapping is the ability to map “data layers” or “themes” of geographically interrelated data for a specific geographic area (or areal extent) and perform analysis of that data and how the layered themes interrelate.

Just imagine for a moment where you are currently located as a point on a map.  Maybe your location is a house or condo?  And the other housing units in your housing development are more of the same types of points.  Each point will have a geo-referenced location (Latitude and Longitude or other coordinate system) in a database along with the street address, and perhaps attribute information about the housing unit (attributes like ‘3 bedrooms, 2 baths, 2-story, 2200 square feet, parcel size of 0.78 acres ’). 

Then imagine all of the streets running through your imagined housing development as another theme or layer.  Add in another layer of utilities such as buried sewer & water pipelines, then another layer for above-ground or buried electrical distribution lines, and yet another for fiber optic cabling, and another layer depicting parcel boundaries, and finally a layer for natural ground cover (trees, open spaces, parks, etc.).  Now in your mind you should be envisioning a full picture of your surrounding area depicted as Points, Lines, and Polygons that either directly or indirectly interacts with each other.

You can then perform analysis of your imagined area using GIS to analyze your imagined features (points, lines, and polygons) by querying the attributes of those data layers, attributes which reside in a database.  For example, you can query the GIS database or 'geodatabase' (also called ‘spatial querying’) for the number of homes in the surrounding area with more than 1500 square feet of living space, or houses with 3 car garages, or with more than 0.5 acres of land, or all of the above.  The resulting query can be seen visually on the map as highlighted points that met your spatial query criteria.  The resulting data from the spatial query can immediately be transformed from a map visualization to tabular data of feature attributes, data aggregations, and data categorizations in graphical forms, as seen in Figure 3.

Figure 3

Layers of geographic data used by a government agency

This type of interrelated geo-referenced data is invaluable for a variety of technical professionals.  For example, civil and environmental engineers, scientists (biologists, geologists, etc.), and city or county planners will use GIS for initially visualizing how layers of environmental data interact (visualized as the composite overlay with all layer combined).

However more than just visualizations can be accomplished with GIS.  GIS provides data analysts with the means to ask the "Where" question of geo-referenced data in an enterprise (or departmental) database.  It allows analysts to select data in ways that are more intuitive than the more routinely used database query.  An analyst can quickly develop 'spatial queries' directly from the map interface that may select geographic data like:
* Display on the map interface commercial real-estate within half a mile of a freeway interchange;
* List or Count the households located within a specifically zoned area; 
* Calculate the number of parcels in a flood plain, affected by wetland land use restrictions, and withing 0.5 miles of known geologic hazards (such as fault lines, landslide scarps, or sink holes).
* Calculate the number of our customers within a 5-mile radius of our retail store and within 10-miles of a large shopping mall.
(these last two examples demonstrate the ability to process multiple factors in a spatial query)

Businesses can use GIS for what is  more recently being termed "Location Intelligence" to evaluate commercial data as part of a Business Intelligence strategy.  For example a retail business may have a successful store and seek to replicate this success by locating their new store based on the demographics of their current successful store location.  Real estate agents can quickly find homes for sale in an area that meet their customer’s requirements.  Transportation companies can develop transit routes and monitor their fleet of vehicles on the fly with transponders and GPS systems.  Insurance companies may monitor the number of traffic accidents in an area and gauge their customer’s insurance premiums accordingly.  And companies, such as utility and pipeline firms, that have geographically dispersed equipment in the field can manage their inventory, direct field technicians, and query equipment locations (for example fire hydrant locations, shut off valve locations, and attribute data on equipment lifespan and dates of service) can all be visualized and queried using GIS. Field technicians can use handheld devices to interact with GIS data implemented as Internet Mapping Services, as depicted in Figure 4.

Figure 4

Display of an Internet Map Service (ArcIMS) 

Depicting Water & Sewer pipelines in Ventura County (with display of feature attributes) 

Finally, GIS can consume and render various types of data.  For example, we discussed in our imaginary setting the visualizations of Points, Lines, and Polygons.  This type of GIS data is called "Vector Data".  But GIS can also depict a data layer as a continuous surface of interconnect pixels.  For example Aerial Photo Imagery, Digital Elevation Models (DEMs), and satellite and LIDAR Imagery is represented as an interconnected fabric of pixels where each pixel represents a data value or color with contextual meaning.  This type of data is called Raster data. 

Figure 5
Depicts GIS layered themes that includes both Vector and Raster data types

You personally may have used either Bing Maps or Google Maps in the past.  These Internet map sites present both forms of data for customers querying Google's or Bing's GIS for visualizations of both vector data (points, lines, and polygons) and raster data (pixel images from satellite images, air photos, LIDAR, and elevation models).  Both forms of data can be depicted together and calculations of areas, and most commonly on Bing and Google maps, routes can be quickly calculated for the areas depicted on the map.

In future blog posts, I hope to expose readers to more detailed information about GIS.  Beyond the current question - "What is GIS?" I intend to delve deeper into what value GIS adds to a data-driven business operation?” And demonstrate how important GIS can be for the successful conversion of geo-referenced data into useful actionable information for Businesses, Governments, Military, and Non-Governmental Agencies.

If you have questions, please feel free to submit a question on this blog site or visit Applied GeoData's website at www.appgeodata.com

Thank you for reading this blog post.

Happy Holidays!

REFERENCES:

Figure 1a - online article "Database Management Systems and Geographic Information Systems"
written by Jack Harrington.
http://www.webzeest.com/article/2131/database-management-systems-and-geographical-information-systems

Figure 1b - ArcGIS 9 Architecture:  Esri ArcNews Online, Spring 2004 edition
http://www.esri.com/news/arcnews/spring04articles/arc9-special/arcgis9-providing.html

Figure 2 - Online Article by ExremeTech: "Think GPS is cool?  IPS will blow your mind" by Sebastian Antohony, April 2012.
http://www.extremetech.com/extreme/126843-think-gps-is-cool-ips-will-blow-your-mind

Figure 3 - Thematic Mapping Image, developed by Farmington Hills, MI GIS Department

http://www.ci.farmington-hills.mi.us/services/CentralServices/GIS.asp

Figure 4 -  ESRI ArcIMS 4.0 Internet Map Service depicting Water & Sewer District Pipelines.  Developed by George Williams for Ventura County Public Works Department in July 2003

Figure 5 - Vector Data and Raster Data data type depiction, developed by Shawnee Professional Services.  http://shawneepsi.com/gis-designs/